PPAR gamma expression in breast cancer: clinical value and correlation with ER beta

Aims: To examine the expression of peroxisome proliferator-activated receptor gamma (PPARgamma) in invasive breast carcinoma in relation to known clinicopathological features, ERbeta, and relapse-free and overall patient survival. PPARgamma is a ligand-activated transcriptional factor that regulates the transcription of various target genes and has been implicated in human breast cancer. Methods and results: We performed immunohistochemistry to detect PPARgamma, ERalpha, PR and ERbeta in 170 infiltrative breast carcinomas. The results were subjected to statistical analysis. PPARgamma was detected in the cytoplasm of 58% of breast carcinoma samples. PPARgamma did not differ with regard to any of the clinicopathological parameters except for histological grade, to which it was found to be inversely correlated (P = 0.019), and ERbeta, to which it was positively related (P = 0.016). As regards relapse-free survival, in univariate statistical analysis PPARgamma was found to exert a marginally favourable impact on all the patients (P = 0.076), but a strong one on patients with ductal carcinoma (P = 0.027), whereas Cox's regression analysis depicted PPARgamma to be an independent prognosticator for patients with ductal carcinoma (P = 0.039). No association was found between PPARgamma expression and overall survival. Conclusion: These results indicate the favourable impact of PPARgamma expression on disease-free survival of patients with ductal breast carcinoma and its possible cooperation with ERbeta in exerting that favourable effect.